Method for transmitting services information in different types of broadcasting networks and unit for processing said information

ABSTRACT

A method for transmitting services information in a broadcasting network by at least one managing center towards a plurality of receivers connected on one hand to a digital data streams broadcasting network of DVB type and on the other hand to a digital data streams broadcasting network of IP type, said streams comprising content data of the services and additional information data on said services structured in tables adapted to the transmission protocol specific to each type of network. The method comprises the steps of exploring the streams broadcasted by the network of type DVB and the streams broadcasted by the network of type IP and extracting services information from these streams, completing an information table, situated at the highest level in the hierarchy of the services information tables, included in the service information DVB-SI transmitted by the DVB network by services information related to the IP network, and transmitting the completed information table in the streams broadcasted by the DVB network towards the receivers having two switchable receiving modules, connected respectively to a DVB and an IP services broadcasting network. The receivers are able to activate the reception of digital data of a service, equivalent to the service currently received, with a second receiving module when the receiving conditions by the first receiving module are degraded.

FIELD OF THE INVENTION

The present invention concerns the field of broadcasting, in a network,digital data streams comprising services and information data towards aplurality of receivers. More particularly, the invention relates to thetransmission and the reception of information data relative to servicesprovided by different types of broadcasting networks. This informationtells a user about access and the characteristics of the servicesavailable from receivers equipped with appropriate interfaces.

BACKGROUND OF THE INVENTION

The DVB (Digital Video Broadcasting) standard defines a service as a setof digital data managed by an operator and broadcasted in a transportstream through terrestrial broadcast or via satellite or via a cabletowards a plurality of receivers/decoders. These data correspondgenerally to television or radio programs, specific information(commercial promotions, stock exchange, weather, events, etc.) or to anyother multimedia application usable one line or after downloading on anappropriate medium.

The transport stream contains data of a service consisting of forexample an audio/video content accompanied by additional data such assub-titles, teletext, or interactive applications and information on theservice such as the content description, the broadcasting time schedule,access conditions etc.

The document EP1464176 describes a method allowing using data providedby the Digital Video Broadcasting—Services Information Event InformationTable (DVB-SI EIT) for accessing to a stream broadcasted in IP (InternetProtocol) mode. A proposed event is associated to at least two sourcesand the system allows a transparent access to this event whatever thesource is. An adequate receiver comprises means of information on theservices allowing using event information data for accessing to thecontent broadcasted according to the Internet Protocol. These means ofinformation use announcement and services description protocols forlinking the services channels made available by the digital contentprovider and by the IP stream broadcasting services.

The document FR2864869 discloses a system for broadcasting DVB servicesvia an IP network wherein signalization information describing thenetwork and the offered services are separated from the servicesthemselves. A receiver connected to a bidirectional network detectsservices by starting connection to a first stream for extractinglocalization information on the network. This information comprise onone hand data on the streams transporting the content of these servicesand on the other hand data on the separated streams transportinginformation on these services. During a final step, the receiver usesthis information for establishing a list of services available on thenetwork.

The document US2003/0078687 describes a method and a system of automaticconfiguration of a listening environment for an optimal soundreproduction based on the characteristics of the transmitted audiosignal and of the service currently received. These characteristics asfor example the broadcasting of the signal in mono or stereo mode aretransmitted via standardized Event Information Table (EIT) used forbuilding the Electronic Program Guide EPG. At reception of thisinformation, the receiver configures itself, if allowed by the hardwareand the system, according to the best mode, i.e. in stereo mode and thiswithout any intervention of the user. According to an embodiment, thedatabase of the program guide and the one of the channel list arecombined and stored in a memory outside of the receiver as for examplein a local server of the system (head end). A partial program guideaccompanying the audio signal can thus be transmitted to the receiverwhich will extract the information necessary for a configuration leadingto an optimal functioning.

The document EP1207698, describes a receiver for digital audio videoprograms comprising a first and a second reception unit receiving eachprograms respectively from a first and a second broadcasting network.These two networks are distinct, as for example a satellite or aterrestrial broadcasting network and an Internet broadcasting network. Aprogram received by at least one of the two reception units isaccompanied, at predetermined periods, by switching instructions fordetermining the reception of a program by one or the other of two unitsof the receiver. The user stores into the receiver information such asfor example a list of favorite programs. At reception of a switchinginstruction the receiver connected to the satellite broadcasting networkswitches to Internet when it detects for example the URL (UniformResource Locator) address of one of the favorite programs of the list.This detection is carried out thanks to Internet selection data (URL forexample) extracted from the Program Map Table (PMT) which PacketIdentifier (PID) is located in the Network Information Table (NIT)transmitted with the audio video content of the program.

The document EP1411723 describes a method for obtaining information onthe programs broadcasted in a transport stream. This information isobtained from Internet links or complete or partial URL contained in theServices Information (SI) or in Program Specific Information (PSI)comprising Program Map Tables (PMT) or Event Information Tables (EIT).The receiver rebuilds, if necessary, the complete path or URL from thereceiver attribution identification data stored therein in order todownload, from the content server thus defined, the information relativeto one or several programs broadcasted in the stream.

In the systems of these documents, the receiver is in charge to exploitthe services available on the network and to extract from the differenttables the information necessary for building a program list. This listis stored in the receiver and made available to an Electronic ProgramGuide EPG displayed on a screen and working as an interface between theuser and the receiver.

In certain configurations, the receiver or decoder also calledset-top-box is connected on one hand to a cable or an antenna and onethe other hand to a bidirectional IP network for receiving DVB servicesstreams. These two broadcasting networks comprising each their ownparameters, lead to a specific processing of the services information bythe receiver. This local processing can occur an overloading of thereceiver particularly when the number, the diversity of the proposedservices and the complexity of their parameters become important.

SUMMARY OF THE INVENTION

The aim of the present invention is on one hand simplifying the serviceinformation data processing by the receiver and on the other handguaranteeing a transparent retransmission of this information on a DVBnetwork without prior exploration of the services available on the IPnetwork by the receiver.

This aim is reached by a method for transmitting services information ina broadcasting network by at least one managing center towards aplurality of processing units connected on one hand to a digital datastreams broadcasting network of DVB type and on the other hand to adigital data streams broadcasting network of IP type, said streamscomprising content data of the services and additional information dataon said services structured in tables adapted to the transmissionprotocol specific to each type of network, the method comprises thesteps of:

-   -   exploring the streams broadcasted by the network of type DVB and        the streams broadcasted by the network of type IP and extracting        services information from these streams,    -   completing an information table, situated at the highest level        in the hierarchy of the services information tables, included in        the service information DVB-SI transmitted by the DVB network by        services information related to the IP network,    -   transmitting the completed information table in the streams        broadcasted by the DVB network towards the processing units.

A processing unit corresponds here to any receiver configured forreceiving and processing of broadcasted digital data such as a decoderor set top box, or a personal computer.

The method of the invention allows grouping in a table transmitted bythe DVB network all the information on the available services whatevertheir source is. The receiver can thus display this information by onlyprocessing the stream broadcasted by the DVB network without processingthe services information broadcasted on the IP network. The analysis ofthe different IP streams and the processing of the services informationdata by the managing center unburden thus the receiver from tasks whichare often considerable.

In fact, the introduction of the IP services information extracted fromthe IP network into tables of a lower level such as the PMT tables(Program Map Table) or the EIT tables (Event Information Table) impliesan analysis of all services and programs broadcasted in the DVB streamin order to insert this information into the correct tables. Atreception, a similar analysis becomes necessary for retrieving the IPservices information.

Among all tables included in the services information data, the NITtable (Network Information Table) is preferably used. It is situated atthe highest level in the hierarchy of the services information tableswith the SDT table (Service Description Table) and the BAT table(Bouquet Association Table). The using of these high level tablesreduces in an important way the tasks of analysis and of processingexecuted on one hand on server side during insertion of IP servicesinformation and on the other hand on receiver side during determinationof the IP service corresponding to the DVB service currently received.

In case of reception problems on the DVB network, the displayedinformation tell the user on the availability of equivalent services onthe IP network. If necessary, the receiver can be switched on the IPnetwork automatically according to a programming of the user interfaceor manually.

The services information data are generally extracted from a structurecalled SD&S (Service Discovery & Selection) transmitted by the IPnetwork. They contain essentially the IP addresses and the descriptorsof the services. According a configuration, they may also include thereferences of the IP broadcasters.

The NIT table groups the set of services data made accessible to a userby an operator. In an example of terrestrial transmission, this tablecontains information necessary for setting up the receiver for getting aDVB stream such as the frequency, the polarization, error correctionparameters, the throughputs of the data streams etc. According to anembodiment the NIT table can be completed with the IP networkinformation received from other ways as the SD&S structure, notably fromfiles, from databases or from a manual capture.

A further object of the present invention is a processing unit ofdigital data services streams comprising a first receiver modulereceiving digital data streams of the type DVB and a second receivermodule receiving digital data streams of the type IP linked to means forprocessing and displaying of broadcasted services information data, theprocessing unit further comprises switching means able to activate thereception of digital data of a service equivalent to the servicecurrently received with the second receiver module when the receivingconditions by the first receiver module are degraded, the equivalentservice being determined by an information table, situated at thehighest level in the hierarchy of the services information tables,comprising the IP addresses and the descriptors of the services of thetype DVB.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood thanks to the following detaileddescription referring to the enclosed figures given as non limitativeexamples:

FIG. 1 shows a plurality of receivers connected to a IP network and to abroadcasting network wherein the distribution of the digital streams isorganized by managing centers.

FIG. 2 represents a block schematic of a processing unit comprising twoswitchable receiver modules, connected respectively to a DVB and an IPservices broadcasting network.

DETAILED DESCRIPTION OF THE INVENTION

The block diagram of FIG. 1 shows a plurality of receivers or set topboxes (STB1 . . . STBn) receiving digital data from a DVB broadcastingnetwork and connected to a IP network. The managing centers (CG1, . . ., CGn) depending on operators are in charge of the organization of thestreams and of their broadcasting on the networks. In the example, thestreams are transmitted to the receivers via terrestrial channels byemitters (E1, E2) or via cable (C) under the control of the managingcenters (CG1 . . . CGn). The method of the invention is thereforecarried out by the managing centers (CG1 . . . CGn) providing theservices and the related information which complies with standardsdefined by the ETSI (European Telecommunication Standard Institute).

The document EN 300 468 entitled Digital Video Broadcasting (DVB);Specification for Service Information (SI) in DVB Systems published byETSI describes the structure of the Services Information (SI) and thestandard ISO/IEC 13818-1 MPEG-2 “Information technology—Generic codingof moving pictures and associated audio information: Systems” definesthe Program Specific Information (PSI).

The PSI data allow configuring the receiver in an automatic way forde-multiplexing and decoding the different program streams it receives.

These PSI data are structured in four types of tables transmitted insections, namely:

1) The Program Association Table (PAT)

It indicates for each service of the multiplex, the localization i.e.the values of the Packets Identifiers (PID) of the packets of thetransport stream of the corresponding Program Map table (PMT). Itprovides also the localization of the Network Information Table (NIT).

2) The Conditional Access Table (CAT)

It provides information specific to the conditional access systems usedin the multiplex comprising the localization of the EntitlementManagement Messages (EMM) stream.

3) The Program Map Table (PMT)

It identifies and indicates the localizations of the streams of eachservice and the localization of the program clock reference fields for aservice.

4) The Network Information Table (NIT)

Its localization is defined according to the standard ISO/IEC 13818-1MPEG-2, the format of the data being not included in this standard. Itprovides information on the physical network such as the designation ofthe emitters (terrestrial or satellites) allowing retrieving othertransport streams on the network. The NIT table, of higher hierarchicallevel relative to the other services information tables such as the EITor PMT tables, describes the organization of the streams, it allowsnotably the receiver to configure itself.

The specific program information PSI is completed by data allowing theuser to identify the services and the events transported in a multiplexor in a network. These data are distributed in tables such as:

-   -   The Bouquet Association Table (BAT) providing besides the name        of the bouquet (set of programs or services made available to        users by an operator), the list of services available in each        bouquet. This table is facultative.    -   The Service Description Table (SDT) containing data describing        services such as the names and the providers of the services.

The two mandatory high levels NIT (Network Information Table) and SDT(Service Description Table) are necessary for adjusting a receiver on aselected program.

The information on the content of the programs appears in the EventInformation Table (EIT) which refers to each service from itsidentification according to the DVB standard. This information describesthe different programs by proposing information similar to the oneprinted in a traditional TV programs magazine. It indicates notably thetitle, the starting time, the duration and the type of the program. Foreach program or service, other written information may complete thecontent data. For example, the information on all programs of the dayand the 7 following days will be transmitted for displaying in theelectronic program guide acting as user interface for an easy programselection. The main information contained in the EIT table is the nameof the event, the starting time, the program duration, the programprogress status, the program title, a summarized textual description ofthe content, the definition of the format of the picture and the sound(16:9, 4:3, mono, stereo, etc.), the exact starting time of a programallowing beginning a recording at the effective start even in case ofdelayed broadcasting of the program in question as done with the VPS(Video Programming System) system.

According to an embodiment, the BAT or SDT tables may be completed bysupplementary services information related to the broadcasting on the IPnetworks in a same way than in the NIT table. This operation is carriedout when the NIT table can not be modified because of restrictionsimposed by services providers.

The document ETSI TS 102 034 entitled Digital Video Broadcasting (DVB);Transport of MPEG-2 Based DVB Services over IP Based Networks specifiesthe deployment of MPEG-2 DVB multimedia services on bidirectional IPnetworks. These IP networks allow broadcasting of important data streamsthanks to the advent of the DSL (Digital Subscriber Line) technologywhich provides them a large bandwidth and a high data throughput.

The Network Information Tables NIT are not used in IP networks, thenecessary information is transmitted in a SD&S (Service Discovery &Selection) structure. This structure provides information on offeredservices and on the way to access these services by means of IPaddresses. It is similar to the one of Services Information (SI) of thetraditional DVB networks which information can be transferred towardsthe appropriate SD&S structure.

The SD&S information can be delivered according to a “push multipointmode” supporting live broadcasting of content or according to a “pullpoint to point” mode for broadcasting content on demand (VOD). Two typesof structures are defined for live broadcasting, namely:

1) “TS Full SI” (Transport Stream full Service Information). This modeallows the transparent retransmission of the transport stream comingfrom other distribution networks (satellite, cable . . . ) comprisingall SI tables without modifications. As the NIT table is replaced by theSD&S structures in the DVB-IP networks, it is ignored by the receiverand the DVB-IP service provider must generate additional servicesdiscover information.

2) “TS Optional SI” (Transport Stream Optional Service Information). Inthis mode, the retransmission of SI tables is optional and it is assumedthat the DVB-IP services provider has other mechanisms for transmittingthe appropriate services information. When the SI tables are present,the SD&S information has priority.

To summarize, the most SI information of the DVB networks areretransmitted either in a transparent way or transferred into SD&Sstructures before transmission in IP networks.

For broadcasting via the DVB networks, the NIT table or other tablesgrouping SI data can be modified by adding of IP networks informationtaken from other sources such as files or databases without having toextract them from the SD&S structures.

A NIT table contains information on the physical organization of themultiplexed streams transported by a given network and on the networkitself. The combination of a network identifier with the transportstream identifier allows identifying in a unique way each transmittedstream. The networks are designated by identifiers or codes definingthem in a unique way according to the document ETSI ETR 162 “Allocationof Service Information (SI) codes for Digital Video Broadcasting (DVB)systems”. The receiver stores the information of the NIT table in anon-volatile memory in order to decrease the access time during theswitching from one channel to another (zapping). A NIT table may betransmitted to other networks than the current one and it isdifferentiated by a table identifier.

The ETSI standards define the organization of the data streamstransmitted with the necessary information for the reception of theservices transported by these streams in function of the receivers'configuration. They let however some freedoms concerning the content ofthe tables, notably the services descriptors which may be adapted to thecharacteristics of the networks whereto the receivers are connected.Thus, the completion, according to the method of the invention, of a NITtable or other tables belonging to the services Information (SI) is notcontraindicated by the standards as long as the introduced informationrespects the prescribed format and syntax.

Because the DVB-SI services information is transmitted by sectionsidentified by packet identifiers PID, The NIT table may be divided intoseveral sub-tables, for example one sub-table by IP servicesbroadcaster. The receiver is then in charge to rebuild a complete tablewhen storing into the non-volatile memory.

The block schematic of the FIG. 2 illustrates a processing unit (STB)comprising a first receiver module (R1) configured for the reception ofservices from the DVB stream and a second receiver module (R2)configured for the reception of services from the IP stream. The unit(STB) further comprises switching means (SW) for activating thereception of the IP services with the second receiver module (R2) whenthe reception of the DVB services with the first module (R1) becomes bador no more possible. The processing and displaying means (P/A) connectedto the processing unit (STB) allow presenting to the user theinformation on the DVB and/or IP services on a television set or anyother visualization screen.

The NIT, SDT or BAT table received by the first receiver module, i.e.via the network of the type DVB, contains the information on theservices broadcasted by the IP network. This table is completed by themanaging center, according to the above described method, with the IPaddresses accompanying the services descriptors and accessorily thereferences of the IP broadcasters.

In case of a bad reception by the first receiver module of a servicefrom the DVB network, the processing unit activates, eitherautomatically or manually by the user according to the displayedinformation, the reception by the second receiver module, i.e. via theIP network, in order to receive one or several services equivalent tothe defective one.

1. A method for transmitting services information in a broadcastingnetwork by at least one managing center towards a plurality ofprocessing units connected on one hand to a digital data streamsbroadcasting network of DVB type and on the other hand to a digital datastreams broadcasting network of IP type, said streams comprising contentdata of the services and additional information data on said servicesstructured in tables adapted to the transmission protocol specific toeach type of network, the method comprises the steps of: exploring thestreams broadcasted by the network of type DVB and the streamsbroadcasted by the network of type IP and extracting servicesinformation from these streams, completing an information table,situated at the highest level in the hierarchy of the servicesinformation tables, included in the service information DVB-SItransmitted by the DVB network by services information related to the IPnetwork, transmitting the completed information table in the streamsbroadcasted by the DVB network towards the processing units.
 2. Themethod according to claim 1, wherein the completed information tableconsists of the network information table NIT defined according to thestandards ETSI EN 300 468
 3. The method according to claim 1, whereinthe completed information table consists of the bouquet associationtable BAT or of the services description table SDT defined according tothe standards ETSI EN 300
 468. 4. The method according to claim 1wherein the information table is completed with at least a descriptorcomprising an identifier of a service and an IP address corresponding tosaid service.
 5. The method according to claim 4 wherein the informationtable is completed with a reference of the broadcaster of the IPservice.
 6. The method according to claim 1 wherein the completedinformation table is transmitted divided into several sub-tables eachattributed to a broadcaster of IP services.
 7. The method according toclaim 1 wherein the information table is completed with the servicesinformation extracted from the SD&S (Service Discovery & Selection)structure transmitted by the IP network.
 8. The method according toclaim 1 wherein the services information concerning the IP network areintroduced into the information table from files or from databases.
 9. Aprocessing unit of digital data services streams comprising a firstreceiver module receiving digital data streams of the type DVB and asecond receiver module receiving digital data streams of the type IPlinked to means for processing and displaying of broadcasted servicesinformation data, the processing unit further comprises switching meansable to activate the reception of digital data of a service equivalentto the service currently received with the second receiver module whenthe receiving conditions by the first receiver module are degraded, theequivalent service being determined by an information table, situated atthe highest level in the hierarchy of the services information tables,comprising the IP addresses and the descriptors of the services of thetype DVB.
 10. The processing unit according to claim 9, wherein theequivalent service is determined by the network information table NITdefined according to the standards ETSI EN 300
 468. 11. The processingunit according to claim 9, wherein the equivalent service is determinedby the bouquet association table BAT or by the services descriptiontable SDT defined according to the standards ETSI EN 300
 468. 12. Theprocessing unit according to claim 9, wherein the reception of thedigital data with the second receiver module is activated automaticallywhen the conditions of reception with the first receiver module aredegraded.
 13. The processing unit according to claim 9, wherein thereception of the digital data with the second receiver module isactivated manually according to the displayed information when theconditions of reception with the first receiver module are degraded.